The moon will turn red-faced early Saturday — but the heavenly treat will be very short-lived.

Diehard lunar fans — lunatics? — will have to rise early to see the so-called “blood moon” during the briefest total lunar eclipse of the century — just 4 minutes and 43 seconds long.

The moon will begin passing through the outer part of the Earth’s shadow — the penumbral stage — a little after 5 a.m., AccuWeather said.

In the New York area, stargazers will see the darkness of a partial eclipse before sunrise at about 6:15 a.m.

In a lunar eclipse, the sun, Earth and moon are aligned — and as the moon passes into the Earth’s shadow, it slowly darkens. When the shadow completely covers the moon, it becomes a deep orange-red because of the distortion by Earth’s atmosphere.

Unlike solar eclipses — when the moon passes between the sun and the Earth — lunar eclipses may be viewed without eye protection.

Four total eclipses of the moon in a row with no partial eclipses in between is called a lunar tetrad. Saturday’s eclipse will be the third “blood moon” in two years, according to AccuWeather.

Anyone who misses Saturday’s event will be able to view the final one in the tetrad, which is set for Sept. 28, 2015.

Eric Edelman, host of a live broadcast of the event beginning at 6 a.m. Saturday on Slooh.com, a robotic telescope service, said the event will be a “Pacific Ocean spectacle,” AccuWeather reported.

The event’s short “totality” — when the moon is fully in the Earth’s shadow — will be because it will only skim the outskirts of our planet’s shadow.

And the reason those in the East won’t see a full total eclipse is because of the moonset.

“In New York City, the moon will be below the horizon at 6:36 a.m. although the partial eclipse from that location would actually end at 9:44 a.m. They only get to see the beginning of the eclipse,” Edelman told AccuWeather.

This tetrad is the second of nine in the 21st century. The third will begin in April 2032.

Skygazers watch the April 2014 blood moon from the water in Melbourne, Australia.Getty Images